It is narrated from Sa'id bin al-Musayyib (may Allah have mercy on him) that a man came to the Prophet (peace and blessings be upon him) and said: "My father is a very old man; if I put him on a mount, he cannot hold himself steady?" He (peace and blessings be upon him) said: "Perform Hajj on behalf of your father."
Hadith Referenceالمعجم الأوسط / باب الميم / 7462
Hadith Takhrij«أخرجه ابن أبي شيبة فى «مصنفه» برقم: 15349»